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description

Lockfile-progs
provides a set a programs that can be used to lock and
unlock mailboxes and files safely (via liblockfile):

mail-lock
- lock the current user’s mailbox
mail-unlock - unlock the current user’s
mailbox
mail-touchlock - touch the lock on the current
user’s mailbox

lockfile-create
- lock a given file
lockfile-remove - remove the lock on a given file
lockfile-touch - touch the lock on a given file
lockfile-check - check the lock on a given
file

By default, the
filename argument refers to the name of the file to
be locked, and the name of the lockfile will be
filename .lock. However, if the
--lock-name argument is specified, then
filename will be taken as the name of the lockfile
itself.

Each of the
mail locking commands attempts to lock
/var/spool/mail/<user>, where <user> is the name
associated with the effective user ID, as determined by via
geteuid(2).

Once a file is
locked, the lock must be touched at least once every five
minutes or the lock will be considered stale, and subsequent
lock attempts will succeed. Also see the
--use-pid option and the
lockfile_create(3) manpage.

The
lockfile-check command tests whether or not a
valid lock already exists.

options

-q,
--quiet

Suppress any output. Success or
failure will only be indicated by the exit status.

-v,
--verbose

Enable diagnostic output.

-l,
--lock-name

Do not append .lock to the
filename. This option applies to
lockfile-create, lockfile-remove,
lockfile-touch, or lockfile-check.

-p,
--use-pid

Write the parent process id
(PPID) to the lockfile whenever a lockfile is created, and
use that pid when checking a lock’s validity. See the
lockfile_create(3) manpage for more information. This
option applies to lockfile-create and
lockfile-check. NOTE: this option will not work
correctly between machines sharing a filesystem.

-o,
--oneshot

Touch the lock and exit
immediately. This option applies to
lockfile-touch and mail-touchlock.
When not provided, these commands will run forever, touching
the lock once every minute until killed.

-rretry-count, --retryretry-count

Try to lock filename
retry-count times before giving up. Each attempt
will be delayed a bit longer than the last (in 5 second
increments) until reaching a maximum delay of one minute
between retries. If retry-count is unspecified,
the default is 9 which will give up after 180 seconds (3
minutes) if all 9 lock attempts fail.

exit status

0

For lockfile-check this indicates that a valid lock
exists, otherwise it just indicates successful program execution.

Not 0

For lockfile-check a non-zero exit status indicates that
the specified lock does not exist or is not valid. For other
programs it indicates that some problem was encountered.